/Engine/Plugins/FX/Niagara/Source/Niagara/Classes/NiagaraSimCache.h
Reads Niagara Position attributes by name from the cache frame and appends them into the OutValues array. Local space emitters provide data at local locations unless bLocalSpaceToWorld is true. EmitterName - If left blank will return the system simulation attributes. LocalSpaceToWorld - Caches are always stored in the emitters space, i.e. local or world space. You can set this to false if you want the local position rather than the world position.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category=NiagaraSimCache, Meta=(AdvancedDisplay="bLocalSpaceToWorld")) void ReadPositionAttribute ( [TArray](API\Runtime\Core\Containers\TArray)< FVector > & OutValues, [FName](API\Runtime\Core\UObject\FName) AttributeName, [FName](API\Runtime\Core\UObject\FName) EmitterName, bool bLocalSpaceToWorld, int FrameIndex ) const